Stabilization of vinyl acetate and particularly vinyl acetate/ethylene copolymers prepared by aqueous emulsion polymerization is typically achieved by the use of surfactants and/or colloidal additives. Surfactants typically consist of ethoxylated alkyl phenols while colloidal additives such as the various grades of poly(vinyl alcohol) (PVOH) and hydroxyethyl cellulose are normally employed in tandem with surfactants. In many cases, the use of such traditional surfactants and/or poly(vinyl alcohol)s singly or in tandem results in drawbacks, such as lack of water resistance, lowered adhesion to certain substrates, little resistance to blocking phenomena which occurs in various coating and non-woven applications, etc.
The following patents are representative of emulsion polymerization processes for vinyl acetate:
U.S. Pat. No. 3,708,388 discloses the preparation of vinyl acetate-ethylene adhesive compositions stabilized by hydroxyethyl cellulose/surfactant mixtures or poly(vinyl alcohol) protective colloids.
U.S. Pat. No. 4,043,961 discloses vinyl acetate-ethylene emulsion compositions prepared in the presence of a protective colloid consisting of a poly(vinyl alcohol)-poly(methyl methacrylate) copolymer, of which about 1-10% by weight is methyl methacrylate.
U.S. Pat. No. 4,267,090 and U.S. Pat. No. 4,287,329 discloses a process for preparing vinyl acetate-ethylene compositions by polymerizing vinyl acetate and ethylene in the presence of (a) 1-2% based on total monomer of a surfactant and (b) a protective colloid consisting of essentially partially hydrolyzed poly(vinyl alcohol).
U.S. Pat. No. 4,542,182 discloses vinyl acetate-ethylene emulsions containing a protective colloid. These comprise a water-soluble polymer containing (a) at least one monomer selected from the group consisting of N-methylolacrylamide and N-methylolmethacrylamide and (b) a water soluble polymer of ethylene glycol having a molecular weight between 1,000 and 50,000.
U.S. Pat. No. 4,921,898 discloses the preparation of a high solids vinyl acetate-ethylene emulsion compositions by polymerizing vinyl acetate and ethylene in the presence of a stabilizing amount of a PVOH/surfactant system consisting essentially of a PVOH having a 100-600 degree of polymerization and a nonionic surfactant consisting of a 30-40 ethylene oxide unit substituted alkyl phenol or a 30-40 ethylene oxide unit substituted propylene glycol.
U.S. Pat. No. 5,124,394 discloses the preparation of vinyl acetate-ethylene emulsion compositions in the presence of a stabilizing and effective amount of essentially poly(ethyloxazoline).
U.S. Pat. No. 5,612,394 discloses aqueous epoxy resin dispersions based upon an epoxy resin, a dispersant, a polymer derived from ethylenically unsaturated monomers, and an amine curing agent. Aqueous epoxy dispersions comprised of 1) a mixture of a prepolymer of an epoxy resin formed by reacting an epoxide with an aromatic phenol, and 2) a dispersant comprising the condensation product of a polyol, typically polyethylene glycol, and an epoxide equivalent is prepared, are dispersed in water and then ethylenically unsaturated monomers polymerized therein. Curing agents for the epoxide are then added to provide crosslinking. The examples at Cols. 15 and 16, disclose the homogenization of epoxy resin with ethylenically unsaturated monomers in a weight ratio from about 10 to 20% monomer to epoxy resin. This is followed by addition of a dispersant and water and, once homogenized, polymerization of the monomers is effected.
U.S. Pat. Nos. 4,415,682 and 5,459,180 discloses polyethylene glycol derivatives for use as dispersants for epoxy resins.